Eligible participants who provide written informed consent will be randomly assigned in a 1:1 ratio to either the intervention group (dalfampridine) or the control group (placebo) using simple randomization. The unit of randomization will be the individual participant, and stratified randomization will not be applied in this study. The random allocation sequence will be generated by an independent statistician, who is not involved in participant recruitment, treatment allocation, intervention implementation, or outcome assessment, using computer-generated random numbers. Participants will be assigned to one of the two study groups according to the allocation sequence in the order of their enrollment. To ensure allocation concealment, the randomization sequence will be placed in sequentially numbered, opaque, sealed envelopes (SNOSE). After a participant is definitively enrolled, the corresponding envelope will be opened in numerical order, and the allocation code will be communicated to the hospital pharmacy. Based on this code, the hospital pharmacy will dispense either dalfampridine or an identically appearing placebo with identical labeling. Drug coding and labeling will be performed by the hospital pharmacy or another independent individual not involved in the conduct of the study or outcome assessment. Consequently, participants, investigators, and outcome assessors will remain blinded to treatment allocation until the completion of the study.